Venturi Metter - Conceptual Question

[FutureEnginr]

I am working on a lab, and *think* I understand what is going on, but looking for a double check of my logic from someone more experience than I am.

In short its a multi-piezometric tube venturi meter, with 1 throat near the begining, a couple of expansions, and a control valve near the end. We took measurements at the various tubes, and I am trying to summarize the data qualitatively.

The 9 piezometric tubes on the pipe are setup as follows: (points A - H)

A) 26mm diameter pipe (13mm in front of the constriction, 25mm long)
B) 16mm throat (16 mm long as well)
C) 26mm pipe that comes after a gradually increasing pipe diameter
D) 51mm pipe that comes after a sharper increasing pipe diameter (totall diffuser = 89mm)
E) A control valve in the 55mm pipe
F) A straight 51 mm pipe section
G) A continued straight 51 mm pipe
H) The end of the meter (still 51 mm diameter pipe, total pipe length = 130 mm)

Here is my understanding is regarding the data we took
(sorry about the formatting, but hopefully you can understand my notes):

(flows) Q (l/s) A(mm) B(mm) C(mm) D(mm) E(mm) F(mm) G(mm) H(mm) I(mm)
flow 1 .18 370mm 332mm 360mm 356mm 360mm 318mm 324mm 322mm 222mm
flow 2 .24 330mm 274mm 320mm 316mm 324mm 254mm 262mm 260mm 160mm
flow 3 .28 370mm 284mm 350mm 346mm 354mm 260mm 272mm 270mm 168mm

Here is what I think happens as water flows through the meter...

'A' p builds due to upcoming constriction
'B' v increases, p drops as water is 'sucked' along
'C' p returns to almost state 'A' (losses occur)
'D' slight drop in p as area increases slightly
'E' p builds in front of valve obstruction
'F' p drops a little after passing valve
'G' p continues to drop as near opening
'H' p still dropping
'I' at end, p as close to 0 as possible (within this system).

Am I on the right track?

Thanks.

 

[Carid]

Sounds pretty reasonable.

I am not any sort of expert in this matter, but did you try to compare the average pressures you found to the radius, cross-sectional area, or volume of the various pipe-sections to detect any relationship?